Sharp tunable optical filters based on the polarization attributes of stimulated Brillouin scattering
Optics Express Vol. 19, Issue 22, pp. 21945-21955 (2011) •doi: 10.1364/OE.19.021945

Sharp and highly-selective tunable optical band-pass filters, based on stimulated Brillouin scattering (SBS) amplification in standard fibers, are described and demonstrated. Polarization pulling of the SBS-amplified signal wave is used to increase the selectivity of the filters to 30 dB. Pump broadening via synthesized direct modulation was used to provide a tunable, sharp and uniform amplification window: Pass-band widths of 700 MHz at half maximum and 1GHz at the −20dB points were obtained. The central frequency, bandwidth and shape of the filter can be arbitrarily set. Compared with scalar SBS-based filters, the polarization-enhanced design provides a higher selectivity and an elevated depletion threshold.